breath.c

/*
 * This replaces the normal pressure target code
 * in the ROM.  Instead of ramping to
 * new values, it commands instantaneous jumps
 * and alternates between 4.0 and the actual target.
 *
 * Put the system in AutoSet mode and use the high-low values
 *
 * mon stm32f2x options_write 0 0x2c ; reset halt ;  flash write_image erase ../stm32-breath.bin 0x8000000

 */
#include "stubs.h"
#include "state.h"

int start(float target, float * base)
{
	// therapy manager variable dictionaries
	float * const fvars	= (void*) 0x2000e948;
	int * const ivars	= (void*) 0x2000e750;

	// don't do anything if we are not in an active therapy mode
	if (ivars[0x6f] == 0)
		return 0;

	// every time through update the max pressure difference
	fvars[0x0d] = 30.0;

	// read current time in microseconds from tim5
	//const volatile unsigned * const tim5 = (volatile unsigned*) 0x40000c24;
	const unsigned now = tim_read_tim5();

	static const unsigned MAGIC = 0xDECAFBAD;

	if (state->magic != MAGIC)
	{
		state->state = 0;
		state->last_change = now;
		state->high_pressure = 0;
		state->low_pressure = 0;
		state->high_time = 0; // microseconds
		state->low_time = 0;
		state->target = 0.0;
		state->smoothing = 3;
		state->sample = 0;
		state->last_value = 0;
		state->magic = MAGIC;
	}

/*
	if ((state->state && now - state->last_change > state->high_time)
	|| (!state->state && now - state->last_change > state->low_time))
*/
	// Use the AutoSet mode to set the "High" and "Low" pressure modes
	unsigned microseconds_per_breath = fvars[0xa] * 250000; // AutoSet low
	float high_pressure = fvars[0x09]; // AutoSet high
	float low_pressure = 4.0; // Default

	// allow the state structure to override the gui defaults
	if (state->state && state->high_time != 0)
		microseconds_per_breath = state->high_time;
	else
	if (!state->state && state->low_time != 0)
		microseconds_per_breath = state->low_time;

	if (state->high_pressure != 0)
		high_pressure = state->high_pressure;
	if (state->low_pressure != 0)
		low_pressure = state->low_pressure;
	
	// check for time to change state
	if (now - state->last_change > microseconds_per_breath)
	{
		state->state = !state->state;
		state->last_change = now;
	}

	// fvars[0x09] == target high
	// fvars[0x0a] == target low
	
	if (state->state)
		state->target = high_pressure;
	else
		state->target = low_pressure;
		
	// smoothly ramp to the new value
	float smooth_target = (state->smoothing * fvars[0x2d] + state->target) / (state->smoothing + 1);

	// and because we need to keep the drawing routine constantly called,
	// add a small value periodically.
	if (now & 1)
		smooth_target += 0.01f;
	else
		smooth_target -= 0.01f;

	fvars[0x2d] = smooth_target;

	// turn off the motor overshoot detector to prevent it from updating fvar[0x34]
	//unsigned char * const motor_overshoot_obj = (void*) 0x200177bc;
	//motor_overshoot_obj[0x10] = 0;

	return 1;
}